KEY POINTS:
New Zealand is heading for its warmest and driest May on record.
As of yesterday, the average temperature for May was 12.6C, almost 2C higher than the average of 10.7C, climate experts said.
Dr Jim Renwick, climate scientist at the National Institute of Water and Atmospheric Research, said it was a significant temperature increase which could turn out to be a record for May since records began being kept in the late 1800s.
Dr Renwick said the relatively mild weather had been predicted to last through to July.
Speculation that the warmer weather was related to global warming could be partially correct, in that over time warmer winters would be expected, but global warming alone could not be used to explain changes in a particular month.
He noted that Europe had had one of its warmest winters and a mild spring, which could be more easily pinned to climate change.
"New Zealand's a bit harder because we have so much variability."
Dr Renwick said parts of New Zealand, such as Gisborne and the Wairarapa, had also had more sun, but only a handful of weather stations reported daily sunshine.
Soil moisture was pretty low in those areas as well as in Hawkes Bay and the southern parts of the North Island, such as Wellington.
Dr Renwick said it was difficult to pick what the snowfalls would be like this winter.
Even with mild autumns, just one decent storm could get the ski season under way if it stayed cold after a big dump and the snow machines were brought out, he said.
Niwa climatologist Stuart Burgess said the warmest Mays on record were those in 1962 (12.3C), 1999 (12.2C) and 1950 (12.1C).
Although there were still a couple of days to go in May the average temperature would probably not change by more than a couple of points so a record was likely.
There were also many sites around the country where lowest-ever rainfall records were likely to be set, mostly down the east coast, he said.
They included Cape Reinga, parts of Auckland, Taupo, the Bay of Plenty, east coast and Wairarapa and in the South Island at Kaikoura and parts of Canterbury and Otago.
Mr Burgess said anticyclones sitting out to the east of the North Island producing warm northwesterly airflows across the country were bringing the good weather.
MetService ambassador Bob McDavitt said the settled weather should remain until the weekend.
At Mt Hutt in Canterbury, ski area manager David Wilson said yesterday that the skifield planned to open on June 9, despite no snow base yet.
"We are not too worried at this stage. We are aiming to open on June 9 but that will depend on snow, of course."
